Forget weight, 85 hp on that boat will push you 60+. (guesstimating, of course).
I've got a 15-foot center console running a 65-horse, and I push 45-50mph! And that's fast when you hit wake/chop/etc.
If it were my boat, I'd look in the 50hp range. Upper 30's to low 40's is awefully fast on the water in the type of boat pictured.
Glen-L sells many similar models, and have researched power. Their typical 15-foot runnies are rated from 60-85hp.
Nothing else matters but how I raise my children ... and their opinion of me, as a father.